I don’t think we found out if most of those games were played with handicaps on or not.
My point about the rating vs ranking system is that they don’t agree on the question, what is the expected skill difference between these two players. This applies even if you don’t play handicap games, in that the distance between 12k and 11k is smaller than the distance between 2k and 1k in Glicko2 points. The difference between 12k and 11k is 49 Glicko2 points. The difference between 2k and 1k is 68 Glicko2 points.
Rating to Rank Conversion Visualized - Internet Go / OGS - Online Go Forum
As I understand it those are the differences in playing strength when a 1 stone handicap begins as well.
I don’t think there is a bug where peoples challenge rank restrictions get ignored, so the difference in strength playing up is always slightly wider than the difference in strength playing down as well on OGS. The underlying system is Glicko2 however so ultimately it’s going to be the closest telling us what the difference is between two players.